alleryE(X) and Var(X) for fair coin tossed n times (success = heads, p = 0.5):
AE = n/2, Var = n/2
BE = n/2, Var = n/4
CE = n, Var = 1
DE = 0.5, Var = 0.25
Answer & Solution
Correct answer: B. E = n/2, Var = n/4
Binomial(n, 0.5): E(X) = np = n/2. Var(X) = np(1-p) = n × 0.5 × 0.5 = n/4.
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